1. Field of the Invention
The present invention relates generally to an electronic device, and more particularly, to an electronic device including an antenna device that provides a wireless transmission/reception function.
2. Description of the Related Art
With the proliferation of multimedia services based on mobile communication services, a need for ultra-high speed and voluminous communication is increasing. Ultra-high speed and voluminous transmission techniques are also needed for data delivery between circuits and between modules inside an electronic device as well as in communication between a base station and an electronic device and between electronic devices. For example, to play high-definition moving images, ultra-high speed and voluminous data transmission is required between a codec-mounted chip and a display module. However, up to date, a transmission line provided between a chip and a display module inside an electronic device is a wired transmission line, which limits the expansion of transmission speed and capacity. With a wired data transmission line, the number of signal lines increases with the expansion of transmission speed and capacity; but in an electronic device designed to be portable, such as a mobile communication terminal, it is difficult to secure enough space therein for installing an expanded, wired transmission line.
Hence, studies have been actively conducted to implement ultra-high speed and voluminous transmission techniques in small spaces, such as inside an electronic device, as well as for wireless communication, by establishing a wireless-type transmission line. For example, a Multiple Input Multiple Output (MIMO) antenna device may implement ultra-high speed and voluminous transmission by using a pattern diversity function.
A technique for implementing a pattern diversity function is described in U.S. Pat. No. 7,253,779 B2 (Aug. 7, 2007). In this U.S. patent, two radiators of different types are disposed or two radiators of the same type are disposed in different directions to obtain a broadside radiation pattern and an endfire radiation pattern.
Another technique for implementing the pattern diversity function is introduced in a paper released in INICA'07 (2007), entitled “A 3-Port Antenna for MIMO Applications”, in which a monopole antenna is disposed on a patch antenna. In this paper, the patch antenna implements a broadside radiation pattern and the monopole antenna implements an endfire radiation pattern.
Further, another technique for implementing the pattern diversity function is described in a paper released in IEEE Antennas and Propagation Magazine (2008), entitled “Compact Multimode Patch Antennas for MIMO Applications”, in which two circular patch antennas having different sizes are disposed on and under a substrate. In this technique, one of the circular patch antennas implements a broadside radiation pattern and the other implements an endfire radiation pattern.
However, the foregoing conventional techniques for implementing the pattern diversity function need two or more antennas, i.e., two or more radiators, to implement different radiation patterns. As a result, a space or a thickness of a substrate for arranging an antenna device increases, and the antenna device becomes difficult to install in a small device. Moreover, as different radiators are used, depending on a desired pattern, fine tuning is required for the same frequency operation, which complicates design of the antenna device.